The present invention is directed to the cooling of molds in a glassware forming machine, and more particularly to liquid cooling of the blank molds and/or blow molds in an individual section machine.
The science of glass container manufacture is currently served by the so-called individual section machine. Such machines include a plurality of separate or individual manufacturing sections, each of which has a multiplicity of operating mechanisms for converting one or more charges or gobs of molten glass into hollow glass containers and transferring the containers through successive stations of the machine section. Each machine section includes one or more blank molds in which a glass gob is initially formed in a blowing or pressing operation, an invert arm for transferring the blanks to blow molds in which the containers are blown to final form, tongs for removing the formed containers onto a deadplate, and a sweepout mechanism for transferring molded containers from the deadplate onto a conveyor. U.S. Pat. No. 4,362,544 includes a background discussion of both blow-and-blow and press-and-blow glassware forming processes, and discloses an electropneumatic individual section machine adapted for use in either process.
In the past, the blank and blow molds of a glassware forming machine have generally been cooled by directing air onto or through the mold parts. Such techniques increase the temperature and noise level in the surrounding environment, and consume a substantial amount of energy. Furthermore, productivity is limited by the ability of the air to remove heat from the mold parts in a controlled manner, and process stability and container quality are affected by difficulties in controlling air temperature and flow rate. It has been proposed in U.S. Pat. Nos. 3,887,350 and 4,142,884, for example, to direct a fluid, such as water, through passages in the mold parts to improve heat extraction. However, heat extraction by liquid cooling can be too rapid and uncontrolled, at least in some areas of the mold, so steps must be taken to retard heat transfer from the inner or forming surface of a mold part to the outer periphery in which the liquid cooling passages are disposed. Various techniques for so controlling liquid-coolant heat extraction have been proposed in the art, but have not been entirely satisfactory.
U.S. application Ser. No. 09/400,123 filed Sep. 20, 1999, assigned to the assignee hereof, discloses a system and method for cooling the forming molds in a glassware forming machine, in which each mold includes a body of heat conductive construction having a central portion with a forming surface for shaping molten glass and a peripheral portion spaced radially outwardly of the central portion. A plurality of coolant passages extend in a spaced array around the peripheral portion of the mold body, and liquid coolant is directed through such passages for extracting heat from the body by conduction from the forming surface. A plurality of openings extend axially into the body radially between at least some of the liquid coolant passages and the forming surface for retarding heat transfer from the forming surface to the liquid coolant passages. The openings have a depth into the mold body, either part way or entirely through the mold body, coordinated with the contour of the forming surface and other manufacturing parameters to control heat transfer from the forming surface to the coolant passages. The openings may be wholly or partially filled with material for further tailoring heat transfer from the forming surface to the coolant passages. The mold body is constructed of austenitic Ni-Resist ductile iron having elevated silicon and molybdenum content. Endplates are carried by the mold body for controlling flow of coolant in multiple passes through the coolant passages. The mold may be either a blank mold or a blow mold.
Although the system and method for cooling molds in a glassware forming machine disclosed in the noted application address problems theretofore extant in the art, further improvements are desirable. In particular, it is desirable to eliminate hoses, tubing and fittings for delivering liquid coolant to and from the mold parts. This liquid coolant flows at elevated temperature, and it is highly desirable to reduce potential damage and leaks in the coolant flow path under the harsh environmental operating conditions of a glassware forming system. Molten glass, abrasive glass particles and spent lubricants can cause damage to the hosing, tubing and fittings. The hoses, tubing and fittings can become loosened or fatigued due to the harsh operating conditions and severe vibration forces during normal operation, and impede rapid maintenance, repair and replacement of the mold parts and operating mechanisms. It is therefore a general object of the present invention to provide a system and method for cooling molds in a glassware forming machine in which all coolant flow passages are enclosed and protected from abrasion and fatigue under the harsh operating conditions of a glassware forming system. Another object of the present invention is to provide a liquid coolant distribution and sealing system that accommodates relative motion between and among system components as the mold bodies are opened and closed.
Briefly stated, the presently preferred system and method of the invention direct liquid coolant to the blank or blow mold halves of a glassware forming machine through an enclosed pivotal rotary union structure, as distinguished from flexible hoses and the like. A coolant manifold is carried by each pivotal mold arm, and communicates with coolant inlet and outlet ports at the lower end of each mold part. The manifold is connected by a floating shaft seal, a rotary union assembly and a crank arm to a coolant source and coolant return in the section box of the associated IS machine section. Each pivotal connectionxe2x80x94i.e., between the section box and the crank arm, between the crank arm and the rotary union assembly, and between the rotary union assembly and the floating shaft sealxe2x80x94comprises a bi-directional rotary union for feeding liquid coolant to the manifold and mold parts, and returning coolant from the manifold and mold parts. Dynamic floating O-ring seals between the coolant manifold and the mold parts, and between the coolant manifold and the floating shaft seal, accommodate relative motion between these components as the mold parts are opened and closed.
More generally, a system for cooling molds in a glassware forming machine in accordance with the presently preferred embodiment of the invention includes a pair of mold arms mounted for movement toward and away from each other, and at least one blank mold or blow mold part carried by each arm and adapted to cooperate with each other to form a glassware forming mold. Each of the mold parts includes at least one coolant passage having an inlet and an outlet disposed adjacent to each other at one end of the mold part. A coolant manifold is carried by each mold arm adjacent to the ends of the mold parts at which the coolant inlet and outlet are disposed, with each manifold having inlet and outlet coolant flow passages coupled to the inlet and outlet of the associated mold parts. A coolant source and a coolant return are disposed in fixed position adjacent to the mold arms, and a pivotal coupling rotary union assembly operatively connects the coolant source and return to the manifold. The pivotal coupling rotary union assembly includes parallel coolant flow paths for directing coolant from the source through the pivotal coupling assembly and the manifold inlet passage to the mold inlet, through the mold part, and from the mold outlet through the manifold outlet passage and the pivotal coupling assembly to the coolant return.
The pivotal coupling rotary union assembly in the preferred embodiment of the invention includes a crank arm assembly having a first crank shaft rotatably coupled to a housing on the section box of the IS machine, a second crank shaft and a crank tie bar interconnecting the first and second crank shafts. The second crank shaft is rotatably received in a shaft link block, as is a manifold tie shaft having a head secured to the side wall of the manifold. Seals in the section box housing and the shaft link block surround the first and second crank shafts and the manifold tie shaft. Parallel coolant flow passages extend from the section box through the first crank shaft, laterally through the crank tie bar, through the second crank shaft, laterally through the shaft link block and through the manifold tie shaft and head to the coolant manifold on the mold arm. In accordance with another feature of the preferred embodiment of the invention, drain passages are formed in the shaft link block, the second and first crank shafts and the interconnecting crank tie bar, and open at each shaft between seals that engage the associated shaft, for draining by force of gravity any coolant that may leak past the seals.
In accordance with another aspect of the present invention, which may be used separately from or more preferably in combination with other aspects of the invention, the mold parts are releasably secured to the associated mold arms by clamps that selectively engage a radial ledge at the lower end of each mold part. Each clamp includes a bridge carried in fixed position on the mold arm, and a lockdown clip carried beneath the bridge for rotation selectively to overlie or clear the ledge on the mold part. Thus, the lockdown clip may be rotated into position to overlie the mold part ledge to hold the mold part ledge on the mold arm, or to clear the mold part ledge so that the mold part may be readily removed by an operator for repair or replacement. A detent locking arrangement between the lockdown clip and the bridge provides for releasable locking of the lockdown clip in either the ledge-overlying or ledge-clearing position of the lockdown clip. A rod preferably extends from the clip through an opening in the bridge parallel to the mold part to a position adjacent to the upper edge of the mold part to facilitate rotation of the lockdown clip into and out of engagement with respect to the mold part. A pin on the mold arm is received in an opening on the underside of the mold part to permit limited rotation of the mold part for self-adjustment with the opposing mold part as the mold arms are brought together.